Catalytic conversion of hydrocarbon oils



1945- DU BOIS EASTMAN ET AL 2,382,039

CATALYTIC CONVERSION OF HYDROCARBON OILS Filed Dec. 10, 1942 ACCUMULATOR (15,2: WW m: A

FRACTIONATORS INVENTORS BY [ii/J W/ m m N M H T m S R A E S a B m m H w c 20 23+. 2 a

m 9 C A S R O T C A E R H 3 J. J V \l u. a l UV a All/V A n 0 OZCkEm ZUOME I? uzumocuJ Patented Aug. 14, 1945 CATALYTIC CONVERSION OF HYDRO- CABBON OILS,

Du Bois Eastman and Charles Richker, Port Arthur, Ten, asslgnors to The Texas Company, New York, N. Y., a corporation of Delaware Application December 10, 1942, Serial No. 468,527

' 4 Claims. (Cl. 196-50) This invention relates to the catalytic conversion of hydrocarbons to convert them to gasoline hydrocarbons suitable for internal combustion engine fuel.

The invention has to do with the catalytic conversion of relatively low boiling oil to produce gasoline or high antiknock value and having a high lead susceptibility. r

In accordance with the invention the feed oil is raised to the conversion temperature under closely controlled conditions of heating and then while in vapor form subjected to the action of an active cracking catalyst under conditions such as to obtain a cracked gasoline of high octane number, low acid heat test, and having a relatively high lead susceptibility.

In our application, Serial No. 383,900, filed March 18, 1941, for Catalytic conversion of hydrocarbon oils, now U. 8. Patent 2,378,292, we have described heating the feed oil to a catalytic conversion temperature in a heating zone under conditions such that the soaking volume factor for the heating zone does not exceed about 1.0. Advantageously in the process of the present invention the heating of the feed oil to the conversion temperature is carried out so that the soaking volume factor does not exceed about 0.5 and preferably is in the range 0.1-to 0.05 and below. Upon heating the oil in this manner, the oil in vapor form is immediately subjected to the action of an active cracking catalyst at a temperature in the range about 800 to 925 F.

An active cracking catalyst suitable for the purpose of this invention is. one of suchactivity that upon passing gas oil of 500 to 700 boiling range in vapor form through a stationary mass of the catalyst in particle form at a temperature of about 950 F. and with a space velocity of about 2 for .a period of about 2 hours without interruption, the yield of debutanized 400 F. end point gasoline obtained amounts toat least by volume of the gas oil, the gasoline having a clear octane number of at" least about 77 to 78 C'. F. R. M.

According to one advantageous form of the invention the heated oil in vapor form is passed through a stationary mass of the catalyst maintained at a temperature in the rangeabout 800 to 925 F. employing a space velocity through the catalyst mass of about 3 or in the range about i 2 to 4 and higher (volumes of liquid oil at 60 F. per hour per volume of catalyst). The reaction may be carried out under a pressure ranging from atmospheric to substantially above 100 pounds,

although a pressure of from 75 to 100 pounds is preferred. The flow of hydrocarbon vapor through the contact mass is advantageously continued for substantially in excess of 1 hour, as, for example, about 2 or 3 hours or more, and even up to 10 hours or more without interruption for reactivation.

In our application, Serial No. 313,654, filed January 13, 1940, for Catalytic cracking of hydrocarbon oils, now U. 8. Patent 2,319,590 we have described a fixed bed catalytic cracking process wherein a gas oil feed in vapor form is passed through a contact mass at a temperature of about 900 to 1050 F., at high space velocity and maintaining the contact mass onstream for substantially in excess of 1 hour as, for example, for a period of from 4 to 20 hours or more without interruption for reactivation.

The present invention also contemplates employing a fixed bed type of operation wherein the contact mass is maintained onstream for several hours without interruption for reactivation but involves charging a somewhat lighter type of feed oil and effecting the catalystic reaction at somewhat more moderate temperatures so as to obtain a gasoline suitable for aviation fuel.

The feed oil is advantageously an oil boiling in the kerosene range and preferably derived from Gulf Coastal and South Texas type crudes. Kerosene derived from such crudes has an octane value in the range 45 to and by the process of our invention it is possible to crack this oil so as to obtain 20 to 25% by volume of butanefree gasoline boiling up to 300 1''. Such gasoline will have a clear octane number of about 79 C. F. R. M. and a lead susceptibility of about 1.1 to 1.3 as measured on the Heb], Rendal and Garton scale which is referred to in an article entitled, Effect of tetraethyl lead on octane numher," by these authors, pages 187 to 191, inclusive of the February 1933, issue of "Industrial and Engineering Chemistry. Thisgasoline is of low acid heat value and therefore has a low unsaturated content. It is further characterized by the presence of appreciable quantities of naph- Aviation dlS- tillate yield,

volume.

. percent Feed oil kerosene octane iSlESt j The aviation distillate obtained in the process of our invention requires no subsequent isoforming or other catalytic reformingtreatment.

In addition to the aviation distillate there is also obtained a naphtha fraction boiling in the range 300 to 400 F. which is characterized by being essentially aromatic as indicated by having an aniline point of about 32 and below. In addition this naphtha fraction also has a relatively low acid heat value of about 5 to 15. It also has a clear octane value of about 82 C. F. R. M.

Kerosene usually has a boiling range of about 400 to 500 .F. and while this type of stock'has been mentioned above nevertheless it is contemplated that the feed oil may be of somewhat broader boiling range, as for example, in the range about 300 to 600 F.

One of the advantages in employing this type of feed stock over the more conventional gas 011 :vol'ume factor is not in excess of about 0.5, the

.7 Hheated oil will contain no measurable quantity of feed is that temperatures as low as 800 to 925 F.

and increased operating pressuresmay be employed without being below the dew point of the feed oil, as may be the case with ordinary gas oil. This temperature range also appears to be most conducive to the production of cracked gasoline of low unsaturated content. When temperatures prevailing in the bed are below the dew point of the feed oil increased carbon deposition occurs upon the catalyst, Thus, by charging a lower boiling feed oil such as kerosene the desired reaction temperatures may be maintained without obtaining excessive carbon deposition on the catalyst which would otherwise necessitate materially reducing the length of time the catalyst mass remains onstream between activations.

. In this connection it is important to carefully control the conditions under which the feed oil is raised to the conversion temperature and for this reason it is desired to operate the heating zone with a low soaking volume factor as will be described in more detail. Prior art teaches heating the oil feed in a heater rapidly and without substantial cracking occurring prior to discharge into a reactor. The object in this, as practiced heretofore was to avoid carbon deposition within the heating coil or heating zone. It has now been found, however, that even though the heating is carried out so as to avoid carbon deposition in the heating zone the heating may still be so severe that certain hydrocarbon products are formed, due to the incipient cracking, which are highly susceptible to carbon formation upon contact with an active cracking catalyst.

It is desirable to avoid thermal cracking with the production of gasoline hydrocarbons prior to contact with the catalyst since the resulting gasoline contains more unsaturated bodies rendering it less suitable for aviation fuel.

Desirable conditions of heating exist when the oil undergoes no change in composition as indicated, for example, by the absence of any reduction in its flash point as the result of heating in the heating zone.

gasoline hydrocarbons.

Also the carbonaceous material subsequently deposited upon the catalyst with a soaking volume factor-in the range 0.5 to 1.0 may be about 1% by weight of the feed oil but will be only about half this amount with a soaking volume factor in the range 0.01 to 0.10. The soaking volume factor may be determined by the method described in the previously mentioned pending application, Serial No. 383,900. e

The invention will now be described with reference to the drawing representing a diagram of flow for carrying out the catalyticcracking of the light oil for the production of high antiknock gasoline.

Referring to the drawing a feed oil such as kerosene obtained from a source not shown is conducted'through a pipe 1 to a heater 2 having a tubular heating coil through which the feed oil passes during vaporization and heating to the conversion temperature. Thus, the oil is vaporized and raised to a temperature of about 900 F., or to a temperature only slightlyhigher than the reactor temperature, the operation being con-- a temperature above 800 F. does not exceed about The heated vapors are immediately passed from the heater through a pipe 3 to the upper portion of catalyst cases 4 or 4'. The pipe 3 should be as short as possible so as to avoid having the heated oil remain at the conversion temperature-for any appreciable timezprior to contact with the catalyst.

The catalyst cases comprise vertical vessels containing'a mass of solid catalytic material such as a synthetic silica-alumina-zirconia catalyst comprising about 80% by weight S102, 10 A and 10% ZrOz. Such a catalyst is an active cracking catalyst having the characteristics previously described. The catalyst may be in the form of powder, pellets, particles, rings, etc.

The vessels are manifolded together as indicated to permit maintaining one vessel onstream while the other is offstream undergoing regeneration. Thus vessel 4 may be regarded as on stream in which case the heated hydrocarbon vapors pass downwardly through the catalyst mass within the vessel during which passage the hydrocarbons undergo conversion. The products of reaction are removed from the bottom of the vessel 4 and are drawn off through a pipe,5 leading to a fractionator 6.

In the fractionator 6 the converted hydrocarbons are subjected to fractionation to form a vapor fraction containing gasoline and naphtha hydrocarbons and normally gaseous hydrocarbons and a higher boiling liquidv fraction comprising gas oil which latter is drawn off through a pipe I for such further disposition as may be desired.

v The vaporfraction is drawn off from the top of the fractionator through a pipe 8 to a second fractionato'r 9 wherein a light gasoline fraction and gaseous hydrocarbons are separated from heavier naphtha hydrocarbons. The light gasoline and gases are drawn oil through a pipe II and a cooler l I to an accumulator l2. Gaseous constituents collecting in the accumulator are drawn oil through a pipe it fromwhich they may be passed to a further process step which may include, for example, further fractionation and catalytic treatment of various constituents thereof. Some of the gaseous hydrocarbons may be returned to the heater I for recycling through the process. V

The liquid portion collecting in the accumulator is drawn off through a pipe i4 and comprises a cracked gasoline suitable for the manufacture of aviation fuel.

A liquid fraction is'drawn off from the bottom of the iractionator I through a pipe II and comprises naphtha suitable for motor fuel production.

The flow of hydrocarbons through the vessel 4 is continued for a period of 2 to 3 hours and may be continued for a-period oi 4 to 8 hours or even more until it becomes necessary to regenerate the catalyst as evidenced by substantial reduction in the rate of conversion.

When regeneration becomes necessary the flow of hydrocarbon vapors is switched from the vessel 4 to the vessel 4' containing fresh or regenerated catalyst. This is accomplished by adjusting the valves in the pipe'manii'olds leading into The regenerating gas is introduced froma;

source not shown through a pipe I! and is discharged from the contact mass through a pipe ll advantageously leadingto a waste heat boiler whereinsensible heat is removed from the gas following which a portion of the cooled gas at a temperature which may range from 750 to 950 F. is recycled. Each catalyst case is advantageously maintained onstream during the cracking operation suillciently long so as, to form a carbonaceous deposit upon the catalyst amounting to not less than 3% and preferably about to 15% by weight of the catalyst.

It has been found that with this amount of carbonaceous deposit upon the'catalyst the catalyst can be reactivated during the regeneration period in such a manner that combustion of the carbonaceous material is confined to a relatively thin section which propagates from inlet to outlet of the reactor in the direction of fluid flow through the reactor. With this type of combustion-it is possible to regenerate with oxygen containing gas as above described, removing all of the heat of combustion as sensible heat of the gas without exposing the catalyst to deactivating temperatures.

Mention has already been made of maintaining the catalyst onstream during the cracking portion of the cycle for periods substantially in excess of 1 hour, as, for example, 2 to 3 hours or more without interruption for reactivation of the catalyst. This is rendered possible since under the preferred conditions of operation the yield of carbon produced during the cracking reaction is substantially less than heretofore, an important reason for this being the close control of the heating of the feed oil to the reaction temperature prior to contact with the catalyst as already described. Reduction in carbon deposition upon the catalyst is also materially reduced by maintaining relatively high rates of fluid flow through the contact mass, as, for example, by operating with a space velocity of about 3 or more.

A further advantage as a result of operating under these conditions is that the ratio of gasoline or gasoline plus gas to carbon obtained during the extended onstream period is substantially greater than that which is obtained when operating with relatively short onstream cracking periods, as for example, periods of 10 to 15 minutes and up to about 1 hour. Thus, the weight ratio of gasoline to carbon obtained when operating onstream for about 4 or 5-hours may be about 81 as compared with a ratio of 38 when operating with an onstream period of about 1 hour.

While a stationary catalyst bed has been referred to above it is also contemplated that the method of controlled heating prior to contact with the catalyst as herein described may also be employed with other types of catalytic reaction systems including the so-called "fluid" catalyst pended within the reaction zone in the presence of the hydrocarbons undergoing treatment.

While a specific silica-alumina-zirconia catalyst has been mentioned above it is also contemplated that other active cracking catalysts may be employed. Various acid treated and metal substituted clays, such as Super-Filtrols are satisfactory. Likewise, the acid treated and metal substituted natural or artificial zeolites such as Doucil can be used. Various metals can be substituted in the clays or zeolites such as uranium, molybdenum, manganese, lead, zinc, nickel, zirconiurn and the like. In general a catalyst is employed which is stable at high temperatures of contrasted with comparatively inactive material cles at a temperature of about 1000 F. and with a space velocity of 2, for a period of 2 hours, a 400 F. end point gasoline yield is obtained amounting to about 4.9% by volume of. the gas oil and which is not more than is obtained by passing the same gas oil vapor through an empty catalyst case under the same conditions of temperature and space velocity. Moreover, the quality of the gasoline obtained is inferior to that obtained with an active catalyst.

By way of specific example a kerosene distillate of about 30.9 A. P. I. gravity, distilling in the range 420 to 507 and having C. F. R. M. octane of about 60, derived from South Texas heavy crude is passed through a tubular heating coil wherein it is heated to a temperature of about 7 920 F. under conditions such that the soaking volume factor is in the range 0.05 to 0.5.

The heated vapors are then passed through a contact mass comprising pellets of silica-alumina-zirconia catalyst such as previously mentioned, maintained at an average reactor temperature of about 870 F. and under an average pressure of about 75 pounds per square inch.

gauge.

The vapors are passed through the contact mass at a space velocity of about 3 (volumes of through a stationary mass of the catalyst maintained at a temperature of about 950" F. and with a space velocity of about 2 for about two hours without interruption, the cracked gasoline obtained amounts to at least 10% by volume of the gas oil and has an octane number of at least about 77 C. F. R. M., and effecting said contact between the catalyst and the heated fraction at a space velocity in the range about 2 to 4 and under a pressure ranging from atmospheric to 100 pounds so as to obtain up to about to volume per cent butane-free high antiknock gasoline boiling up to about 300 F.

liquid kerosene at 60 F. per hour per volume of catalyst) tact mass is continued for a period of about 2 hours obtaining the following average yields, basis charge: I

The aviation distillate comprises Ci-free hydrocarbons boiling in the range about 95 to 300 F. having a gravity of about 64 and a clear C. F. R. M. octane number of 81.

The heavy naphtha fraction has a gravity of A. P. I. and boils in the range 300 to 402 F., having a clear octane value of about 82. v

The aviation distillate has an acid heat value of about 50 as compared with a value in the range about 100 to 250 forcatalytically cracked naphtha as produced heretofore under more conventional operating conditions. The heavy naphtha fraction has an acid heat value of about 5 to 15.

Moreover, the distillate may be finished up quite eflectively with a light acid treatment followed by neutralization and steam distilling. The acid treatment may pounds of acid per barrel of hydrocarbons being treated. The acid advantageously comprises spent alkylation acid such as disclosed in U. S. 2,267,458. The finished gasoline distillate will hav a clear C. F. R. M. octane number of about 79.5 and upon addition of the octane number will be about 92. plus, I

be effected with about 3 to 10 2. Process according to claim 1 in which the kerosene fraction 'hasaC. F. R. M. octane of I abOllt 58 to 60.

3. A process for tlfe manufacture of high antiknock gasoline of high lead susceptibility boiling within the range up to about 300 F. which comprises obtaining from naphthene base crude pe-,

troleum a hydrocarbon feed boiling within the range about 300 to 600 F. and having a C. F. R. M.octane value in the range about to 60, heating said feed to a temperature in therange about 800 to 925 F. under conditions such that there is substantially no conversion of said feed Aviation distillate Percent by volume 18.8 Heavy naphtha do 10.0 Gas 011--. do.. 65.0- Isobutane do 2.9 Normal butane do 1.2 Butylene-2 do "0.8

Butylene-l and isobutylene do- 0.4 Ci-free gas By weight 2.4' Carbon do 0.3

hydrocarbons into gasoline hydrocarbons as a result of said heating, immediately subjecting the heated fraction in vapor phase to contact with a solid cracking catalyst of such activity that upon passing gas oil vapor through a stationary mass of the catalyst maintained at a temperature of v about 950 F. and with a space velocity of about 2 for about two hours without interruption, the cracked gasoline obtained amounts to at least 10% by volume of the gas oil and has an octane number of at least about?! C. F. R. M., and effecting said contact between the catalyst and the heated fraction at a space velocity in the range about 2 to 4 and under a pressure ranging from atmospheric to 100 pounds so as to obtain a substantial yield of butane-free high anti-knock gasoline boiling within the range up to about 300 F.

4. A process for the manufacture of high antiv octane value in the range about 45 to 60, heating said fraction to a temperature in th range 4 cos. of lead tetraethyl Obviously many modifications and variations 0 of the invention as above set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated by thev appended claims.

We claim:

1. Process for the manufacture of high antiknock gasoline of high lead susceptibility boiling within the range up to about 300 F. which comprises obtaining from naphthene base crude pekerosene fraction having a C. F. R. M.'-'

troleum a octane value in the range about'45 to60, heating 800 to 925 F. under conditions such that the heated fraction contains no measurable quantity of gasoline formedas a result of said heating,

immediately subjecting the heated fraction in I vapor phase to contact with a solid cracking catalyst of such activity that upon passing gas oil vapor through a stationary mass of the catalyst maintained at a temperature of about 950 and with a space velocity of about 2 for about two i hours without interruption, the cracked gasoline obtained amounts to at least 10% by volume of the gas oil andhas an octane number'of at least I 1 about 77 C. F. R. M., and effecting said contact said fraction to a temperature in the range 800 to 925 F. under conditions such that the heated: fraction contains no measurable quantity 'of gasoline formed as a result of said heating, imme heated fraction in vapor diately subjecting the phase to contact with a solid cracking catalyst of such activity that upon passing gas oil vapor;-

between the catalyst and the heated fraction at a space velocity in the range about 2 to 4 and under a pressure ranging from atmospheric to p pounds so as to obtain a substantial yield of butane-free high anti-knock gasolin boiling within the rangeup to about 300 F.

DU 1301s EASTMAN. CHARLES RICHKER. 

